China, 1662-1670 AD., Ch'ing dynasty, emperor Sheng Zu, Jiangning / Nanking mint, 1 Cash, Schjöth 1433.

China, Ch'ing (Qing) dynasty (1644-1911 AD.), emperor: Sheng Zu (Sheng Tsu) (1662-1722), reign title: Kang Xi (Kang Hsi) (1661-1722), Jiangning mint (or Nanking, Jiangsu province), issued 1662-1670 AD.,
1 Cash (21 mm / 2,25 g), cast brass, square center hole, trimmed edge, very worn,
Obv.: 康 熙 通 宝 , four chinese characters - (top-down-right-left) around square center hole: Kang Xi Tong Bao (Kangxi tongbao, Kang Hsi T'ung Pao, K'ang Hsi T'ung Pao).
Rev.: Ning (in Manchurian) to the left, Ning 寧 (simplified 宁) (in Chinese) to the right..
Schjöth 1433 ; KM 328 ; Ding 2254 .

This is one - the "Ning" part - of a series of twenty coins known as "poem" coins (shi qian), which, according to folklore, have talismanic qualities when placed together. The coins were put in a specific order in which the mint names formed a “poem.” The poem did not have a particular meaning, but rhymed according to the rules of classical Chinese poetry.
T'ung Fu Lin Tung Chiang,
Hsuan Yuan Su Chi Ch'ang,
Nan Ho Ning Kuang Che,
T'ai Kuei Shen Yun Chang.

from http://ykleungn.tripod.com/kanghsic.htm about the mint:
In the Qing Dynasty, the mint marks in both Chinese and Manchu characters on the reverse of the coin are normally indicated where the coin was cast. But the identifying character of this coin, "Ning" in both Han and Manchu script on the reverse is used for Ninghsia Mint (now Kansu) or Kiangning Mint (now Nanking of Kiangnan province)? The third suggestion for this mint mark is Ningpo Mint of Chekiang Province.
According to the book "Ku Ch'ien Kao Lueh" wrote by Mr. Ch'ien Wu Chiu in the Taokuang period (1821-1850), "Ning" is used for Kiangning Mint of Kiangnan province.
On the other hand, I find that there is no record of Ninghsia Mint and "Ning" is referred to Kiangning Mint in the official record , "Ch'ien Pi K'ao" of "Ch'ing Ch'ao Wen Hsien T'ung K'ao", ( A Comprehensive Historical Compendium of the Documents of the Qing Dynasty, numismatics) wrote in the Chien Long period (1736-1796).
On the contrary, character "Ning" is referred to Ninghsia Mint in "Chih Ch'ien T'ung Kao" (A Comprehensive study of Chinese Coin) wrote by Mr. T'ang Yu K'un in 1852.
Most of the 20th-century numismatists, including Mr. Ting Fu Pao, author of "A dictionary of ancient Chinese coins." and Mr. Pang Hsin Wei, author of "The Currency History of China", believed that "Ning" was used for Ninghsia Mint, but I think both of them were followed the informations provided by the book "Chih Ch'ien T'ung Kao".
Mr. Fr. Schjoth had wrote that "Ning" was used for Ningpo Mint in Chekiang Province in his book about Chinese currency.
About the identifying character of this coin, "Ning", I thought about it over and over, and decided that it should be applied to Kiangning Mint (now Nanking).